Antenna system producing a millimeter wave beam having a gaussian-like distribution

Abstract

An antenna system for producing a millimeter wave beam having a Gaussian distribution uses a high power source and a partial mode converter operatively coupled to the source and reviving from the source a T m ,n mode wave which might either be TE m ,n or TM m ,n'. The converter delivers a mixture of modes including the mode T m ,n at a relative power rate of 70 to 85% and at a relative phase 0, and at least one of the following additional modes, namely T m ,n-1 at a relative power rate of 10 to 20% and at relative phase π, and TE m ,n+1 at a relative power rate of 10 to 20% and at relative phase π. The mixture of modes is applied to a collimation reflector (3, 10), having a concentration point (5) constituting the antenna system outlet. The antenna system can convert any T m ,n mode into a linearly polarized narrow beam of very high power (about 1 MW) and and of high frequencies above 100 GHz.

We claim: 
     
       1. An antenna system for producing a millimeter wave beam having a Gaussian-like distribution, said system comprising: a high power source, a partial mode ocnverter operatively coupled to said source, said source comprising means for supplying to said partial mode converter a T m ,n mode wave of the group consisting of TE m ,n and TM m ,n, said partial mode converter comprising means for delivering a mixture of modes including a mode T m ,n at a relative power rate of 70 to 85% and at a relative phase 0, and at least one additional mode of the group consisting of T m ,n-1 at a relative power rate of 10 to 20% and at a relative phase π, and TE m ,n+1 at a relative power rate of 10 to 20% and at a relative phase π, and said system further comprising means for applying said mixture of modes to collimation reflector having a focus concentration point constituting an antenna system outlet. 
     
     
       2. An antenna system according to claim 1, further comprising a corrugated reflector for converting an axially symmetric electric field of the incident wave into a linearly polarized Gaussian-like beam TEM OO  mode and wherein said corrugated reflector is disposed in the path of the wave constituted by said mixture of modes at the outlet of said partial mode converter. 
     
     
       3. An antenna system according to claim 2, wherein the corrugated reflector is placed in the path of said wave along with the collimation reflector, and said collimation reflector is downstream of said corrugated reflector. 
     
     
       4. An antenna system according to claim 1, wherein the collimation reflector is a corrugated reflector. 
     
     
       5. An antenna system according to claim 1, wherein said source emits an electron beam, said collimation reflector is located immediately downstream of the source, and is provided with a central hole allowing said electron beam to pass therethrough. 
     
     
       6. An antenna system according to claim 1, wherein said partial mode converter comprises means for forming a mode mixture wave containing both T m ,n-1 and T m ,n+1 additional modes of approximately equal power rates.